1. Technical Field
This invention relates in general to digital communications and in particular to the management and processing of data streams in a manner which permits variable constructs to be represented within a structured data stream.
2. Background Art
Management of a data stream in a digital communications network, such as a local area network (LAN), or larger teleprocessing networks, presents many problems, particularly when it is desired to represent a variable construct within a data stream which is highly structured. By variable construct, what is meant is a general variable data expression within a data stream which is derived as a result of processing a general variable data description or definition which is composed of a sequence of data stream controls, the content of which vary depending upon the general variable description, the triggers which cause processing of the control sequence to occur and the linkage of the general variable to other constructs within the data stream.
Certain known systems exist which permit the inclusion of selected variable data within a data stream as long as the variable data is constrained to a preselected structured field. However, these systems do not permit the utilization of truly variable data nor do they permit an efficient utilization of data stream resources.
Recently, a data stream management system has been proposed which utilizes an off-line shell structure which includes formatting and processing information which may be utilized to manage and process tagged constructs or elements that are independent of the data content, but may appear concurrently with the data in a data stream representation of a document created by an editor or other similar application. The shell structure may be located off-line, or separate from the data stream and transmitted independently from the data stream, or it may be located within the data stream and transmitted therewith.
The above-referenced system includes a tag element function which links constructs in a data stream by referencing named constructs in the shell structure. The constructs in a shell structure specify the rules, relationships, and formatting information that govern the processing and management of a portion of the data stream. While this system represents an advance in the efficiency and flexibility of data stream management, it is designed to control the processing of data stream content and cannot be utilized to create, evaluate, or calculate the status of previously nonexistent data which may then be utilized to process a portion of the data stream.
Therefore, it should be obvious that a need exists for an improvement in data stream management techniques which permit the utilization of variable data within structured data streams.